Respiratory positive expiratory pressure (PEP) devices are used to assist in exercising patient's lungs and maximising lung function. PEP therapy is desirable for the treatment of conditions affecting respiratory function such as cystic fibrosis, asthma, chronic obstructive pulmonary disease (COPD), and chest infections. Additionally, such therapy is often required following surgery, or during periods of bed rest. These PEP devices provide above atmospheric pressure at the airway when the patient exhales, thus creating resistance. The action of the patient exhaling against the positive pressure exercises the patient's lungs to improve the health of their lungs. Use of PEP therapy promotes reduced air trapping and assists in optimisation of delivery of bronchodilators for the treatment of asthma and COPD. The technique has also been used in the treatment and prevention of atelectasis, and to enhance secretion mobilisation for treatment of cystic fibrosis, chronic bronchitis and bronchiectasis.
PEP devices are generally used in a hospital environment under the direction and guidance of a physiotherapist or other qualified person. However, in certain circumstances it is advantageous for the patient to be able to take the PEP device home to continue treatment once they have been discharged from hospital.
Commercially available respiratory PEP devices are available. Such devices include oscillatory PEP devices which use oscillating steel bearing technology (eg Flutter®, Acapella®). Exhalation by a patient into the valve of an oscillatory PEP device causes a steel ball bearing to oscillate at a high frequency. This results in intermittent positive expiratory pressure and vibration of the patient's airways with the subsequent expectoration of mucus. Devices of this type are generally too expensive for purchase in bulk by a hospital or other organisations. Furthermore, they may be considered too expensive, too fragile or too complicated for use and maintenance by the patient at home.
Bubble positive expiratory pressure devices (Bubble PEPs) have been used by physiotherapists working in the field of cardiorespiratory services. Bubble PEP therapy has been achieved using equipment assembled from a bottle, such as a saline bottle or milk bottle, containing water and a piece of tubing. One end of the length of tubing is inserted into the water, typically at a depth of approximately 10 cm below the water surface. The head of water produces a positive expiratory pressure when the patient exhales through the other end of the tube.
Use of this type of bubble PEP device presents potential hygiene and safety concerns. The current bubble PEP devices cannot be easily and effectively cleaned thus posing contamination risks. There is a risk of aspiration pneumonia or choking occurring if a patient accidentally inhales the liquid into the lungs. Furthermore, the equipment is awkward to use, is not portable and does not produce a reliable or reproducible performance. The resistance produced is inconsistent since there are no markings on the saline or milk bottle to indicate the amount of water necessary to provide the required level of positive pressure. Furthermore the tubing is not easily fixed in place, so the end can move during use causing fluctuations in the level of resistance produced. The equipment is awkward to handle and time consuming to assemble. It can be knocked over easily, and water can be spilled. This form of equipment cannot be readily transferred home with a patient when the patient is discharged from hospital, so is limited to use in the hospital environment. Moreover, use of such devices may be unacceptable in accordance with health related regulations and guidelines.